The invention is in the field of lamps for automobiles and other vehicles, such as headlamps and fog lamps, having truncated reflectors, i.e., reflectors having a concave surface which is truncated at the top and/or bottom.
Certain headlamp reflectors are truncated at their top and/or bottom to reduce their vertical height for better fitting and styling in automobiles. In these and other types of headlamps, a shield or other means is used to achieve sharp beam cutoff to reduce glare above the horizontal, specifically in low-beam lamps used for city driving. U.S. Pat. Nos. 1,359,789 to Brown and 4,276,583 to Fratty disclose truncated headlamps, in which Brown employs an auxiliary reflector and Fratty employs a shield to reduce glare. Attempts to design truncated headlamps having reduced glare, without the use of internal shields, have not been completely successful, especially where the filament is enclosed in a glass inner bulb.